1. Field of the Invention
The present invention relates to an ignition coil for an engine.
2. Description of the Prior Arts
Heretofore, it has been a conventional method of manufacturing an ignition coil for an engine by winding a primary coil around a coil bobbin of a primary side, attaching a terminal coupler to the coil bobbin, pulling coil wire of the primary coil out of the coil bobbin at a leading end and a trailing and of said primary coil and then connecting each of the coil wires at the leading and trailing ends of the primary coil to each terminal of the coupler by soldering process.
According to such conventional method, it is required to connect the coil bobbin and the terminal coupler, which are prepared as separate parts, and it is also required to take steps of stripping or covering of the coil wire, winding the stripped coil wire around the terminal of the coupler and then soldering the coil wire to the terminal. This conventional manufacturing method is disadvantageous in that it requires a large number of parts and it is low in its working efficiency.
On the other hand, in case of an ignition coil for an engine of the type where a C-type core part is assembled in a coil case which is arranged to assemble a coil unit therein so that a side of said C-type core part is passed into said coil case, and an I-type core part is pressed into engagement with an opening end of said C-type core part to form a construction in which the core consisting of the C-type core part and the I-type core part is integrally assembled in the coil case, it is necessary to provide a clearance between the coil case and the I-type core part which is pressed into engagement with the C-type core, in order to allow the pressure engagement of the I-type core part to the C-type core part.
Owing to the existance of such clearance, the ignition coil of this type tends to cause a play between the core and the coil case after assembling.
In order to avoid such disadvantage, it has been heretofore necessary to fill the clearance between the coil case and the core, after assembling the core to the coil case, with an adhesive material to fixedly connect the core to the coil case. However, such use of the adhesive material requires the core adhering step, so that the working efficiency at the time of manufacturing ignition coils is lowered.